In an effort to optimize polymer properties for specific applications at the lowest cost, polymers are often blended together. Numerous blends comprising thermotropic liquid crystalline polymers (LCP's) and isotropic polymers have been reported in the literature. These include blends of LCP's with polyethylene terephthalate (U.S. Pat. No. 4,489,190), polyphenylene sulfide (U.S. Pat. No. 4,276,397), polycarbonate (U.S. Pat. No. 4,460,735), polysulfones (U.S. Pat. No. 4,460,736), and many other isotropic polymers (e.g., U.S. Pat. No. 4,386,174 and 4,792,587). These blends are generally made by mixing the polymers as solids, usually in the form of pellets, and feeding them together into an extruder, where they are melted and mixed together under shear to yield a uniform blend.
Generally these polymers are not miscible, and the blends are composed of individual domains of one polymer in the second polymer. The properties of the resulting blends typically are the weighted average of the properties of the individual components of the blend (i.e., they follow the rule of mixtures). More often, the properties of the blends are less than predicted by the rule of mixtures.